JPH03127097A - Drawing method for vector font - Google Patents

Abstract

PURPOSE:To increase the speed of drawing which uses the vector font by referring to stored coordinate values and calculating the outer product of two vectors, and determining a triangle to be painted out. CONSTITUTION:A processor 1 reads a program out of a ROM 2, reads the coordinate values of a vector for drawing the contour of a character stored in a RAM 3 to draw the contour of the character on an image memory 4, and paints out the bits in a closed area segmented with the contour. For example, it is checked whether there are other points in a triangle DELTAABC and when not, the inside of the triangle DELTAABC is painted out. Then the coordinate value of the RAM 3 indicated by a point B is given a deletion mark and the operation is finished when the number of dots which are not given the deletion mark reaches two. Consequently, a drawn character can be painted out quickly on a vector font basis.

Description

[Detailed Description of the Invention] [Summary] Regarding a vector font drawing method that enables high-quality characters to be drawn at high speed, the present invention aims to speed up the drawing speed of vector fonts by drawing outlines of characters. Coordinate values indicating the position of the reference point of the vector to be drawn are sequentially memorized in the order in which the outline is drawn, and are stored in the process of a character information output device that creates a character by filling in the inside of the character outline drawn by the vector. The vector AB and Vector A
Find the cross product of C, check whether the reference point C is inside the character outline with respect to the vector AB, and if the reference point C is inside the character outline, are there other reference points inside the triangle ΔABC? If there is no other reference point inside the triangle ΔABC, fill the inside of the triangle ΔABC and add a deletion mark to the coordinates of the reference point B, and if the reference point C is not inside the character outline. , if there is another reference point inside the triangle ΔABC, or if the interior of the triangle ΔABC has been filled, a new arbitrary reference point A is created.
By repeating the above operation after determining , the filling operation is terminated when the number of reference points that are not marked for deletion reaches 2.

[Industrial application field]

The present invention relates to a character information output device for an information processing device, and more particularly to a vector font drawing method that enables high-quality characters to be drawn at high speed.

Personal computer, word processor and CAD
As a character information output device for information processing devices such as systems,
Printers, graphic display devices, etc. are used. As printers, graphic display devices, etc. become more sophisticated, there is a demand for improved quality of displayed or printed characters.

By the way, in existing character drawing methods, character fonts are stored in advance in a ROM, etc., and characters are displayed by reading out the character fonts and developing them on an image memory. When displaying characters by changing the size of the characters, the character font read from the ROM is enlarged or reduced, but this causes irregularities to appear on the curved portions of the characters, resulting in a significant drop in character quality.

To avoid this, a drawing method using vector fonts has been proposed, but it is desired that this drawing speed be fast.

[Conventional technology]

The conventional method for drawing characters using vector fonts is to draw the outline of the character using vectors on image memory, then
A method is used to fill in the bits inside the closed area.

[Problem to be solved by the invention]

When the outline of a character is drawn using vectors, several closed regions are formed. Therefore, characters can be drawn by filling in this closed area.

However, conventionally, in order to detect this closed area, scanning was required to search for the outline of the character drawn in the image memory. That is, while sequentially reading out the memory contents in the main scanning direction,
When the bits are checked and two black dots indicating boundary points are detected, a process is performed to make all the areas between these two black dots black.

Therefore, there is a problem that the filling operation time becomes longer and the drawing speed is greatly influenced by the memory access speed.

In view of these problems, the present invention aims to increase the drawing speed of vector fonts.

[Means to solve the problem]

FIG. 1 is a process flowchart showing the configuration of the present invention.

FIG. 1 shows the flow of processing by a processor that controls a character information output device, and 5 to 9 are processing steps.

That is, the coordinate values indicating the position of the reference point of the vector for drawing the outline of a character are sequentially memorized in the order in which the outline is drawn, and the inside of the character outline drawn by the vector is filled based on the coordinate values to draw the character. In the character information output device that creates a Based on the coordinate values of the reference point C adjacent to the reference point B, the cross product of the vector AB and the vector ACO is obtained, and in step 6, it is detected whether or not the Bfj reference point C is inside the character contour with respect to the vector AB. , If the reference point C is inside the character contour, in step 7 it is checked whether there is another reference point inside the triangle ΔABC, and if there is no other reference point, in step 8 the triangle ΔA is
Fill in the inside of BC, add a deletion mark to the coordinates of the reference point B, and specify that it will be excluded from subsequent processing, and in step 6, if the reference point C is not inside the character outline, If there is another reference point inside triangle ΔABC in step 7, or if the interior of triangle ΔABC has been filled in in step 8, return to step 5 and define a new arbitrary reference point A. By repeating the above operation, when the number of reference points of the vector to which the deletion mark has not been added reaches 2 in step 9, the filling operation is completed.

[Effect]

By configuring as above, by referring to the stored coordinate values and calculating the cross product of two vectors,
In order to determine the triangle to be filled, there is no need to search the character outline developed in image memory as in the past, and it is now possible to speed up the filling of drawn characters using vector fonts of high character quality. It is possible to draw high-quality characters at high speed.

〔Example〕

FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention.
FIG. 3 is a diagram illustrating the operation of FIG. 2.

The processor 1 reads a program stored in the ROM 2 and operates it, reads out the coordinate values of a vector for drawing the outline of a character stored in the RAM 3, and stores the coordinate values in the image memory 4.
The outline of the character is drawn, and the bits within the closed area defined by this outline are filled in.

The RAM 3 stores, for example, coordinate values of reference points of vectors based on contour figures as shown in FIG. That is, the coordinate value χ1. indicating the reference point A. The coordinate values from Y1 to □Y8 indicating the reference point H are sequentially stored, for example, as shown below.

X,,Y.

X,,Y.

X3・Ygo X,,Y.

X,,Y.

X&, Y&X? , Y? XIl, Y8 The above arrangement shows that each vector is drawn sequentially in a clockwise direction (hereinafter abbreviated as rightward) with point A as a reference. The processor 1 first selects an arbitrary point from the coordinate values recorded in the RAM 3, and uses the coordinate values X, , Y, of point A as the starting point, and calculates the coordinate values Xt, yz of the second point B. Read out.

Then, vector AB is determined based on these two points A and B.

Next, Prosensor 1 calculates the coordinates of the third 0 point, X3°Y,
The point C with this coordinate value XIY3 is the vector A
Check whether it is to the right of B or in the opposite direction from clockwise (hereinafter abbreviated as left direction). That is, it is determined whether the sign of the vector obtained by calculating the outer product of vector AB and vector AC is positive or negative.

Since vectors AB and AC exist on the X, Y plane,
It can be determined whether the 0 point is to the right or to the left of point B just by the sign of the vector obtained by the cross product.

As in this example, when point 0 is to the left of point B, the sign of the vector obtained by the cross product of vector AB and vector AC is positive, so processor 1
The interior of the triangle ΔABC formed by , B, and C is not filled. This is to prevent unnecessary areas from being filled in.

Here, the processor l selects, for example, point B as an arbitrary point, reads the coordinate values Xt, 'it of point B, and uses this as a starting point to read the coordinate values X2+YI of the second point 0. Then, a vector BC is obtained based on these two points B and C, and the coordinate value of the third point D is set to 4. Read v4 and add 4 to this coordinate value. Check whether the dot with Y4 is to the right or left of vector BC.

Since the sign of the vector obtained by calculating the cross product of vector BC and vector BDO is negative in this example, processor Check if it exists. That is, the processor 1 determines that the position of each point indicated by the coordinate values stored in the RAM 3 is a vector B that constitutes three sides of the triangle ΔBCD.
C.CD.

Check whether it is on the right side of the DB.

If even one point exists inside the triangle ΔBCD, read the coordinate values of the second point from point B to find the vector, and then
Redo the operation of reading the coordinate values of the point. This is to prevent unnecessary areas from being filled in.

If there are no other points inside the triangle ΔBCD, the drawing memory 4
Fill in the inside of the triangle ΔBCD formed by the three points B, C, and D above, add a deletion mark to the coordinate value X3+Ys of the second 0 point stored in RAM3, and point C will no longer exist. Treated as such.

Next, the processor 1 selects, for example, point D as an arbitrary point, reads the coordinate ti value Xa=Ya of point D, and uses this as a starting point to read the coordinate values Xs, Ys of the second point E. Then, calculate the vector DE based on the two points E, read out the coordinate values Xh and Yh of the third point F, and calculate that the point F with this coordinate (iX□y6) is in the right direction of the vector DE. Check if it is there or to the left.

Since the sign of the vector obtained by calculating the cross product of the vector DE and the vector DF is negative in this example, next, if there are other points inside the triangle ΔDEF formed by the three points of the processor 1, E, and F, Check if it exists.・That is,
Processor l checks whether the position of each point indicated by the coordinate values stored in RAM 3 is on the right side of vectors DE and EFFD forming three sides of triangle ΔDEF.

If even one point exists inside the triangle ΔDEF, read the coordinate values of the second point from point D to find the vector, and then
Redo the operation of reading the coordinate values of the point.

If there are no other points inside the triangle ΔDEF, the drawing memory 4
When the interior of the triangle ΔDEF formed by the three points above, E and F is filled in, the second point E stored in RAM3 is filled in.
A deletion mark is added to the coordinate values X,,Y, of the points, and point E is treated as not existing from now on.

Next, the processor 1 selects, for example, point B as an arbitrary point and fills the inside of the triangle ΔBDF in the same manner as described above, and then the coordinate value Xa of the second point D stored in the RAM 3
, Ya are added with deletion marks, and subsequent points are handled as if they do not exist.

Next, the processor l selects, for example, point B as an arbitrary point and fills the inside of the triangle ΔBFG in the same manner as described above, and then the coordinate value X of the second point F stored in the RAM 3,
A deletion mark is added to , Y, and from now on point F is treated as not existing.

Next, when the processor 1 selects, for example, point B as an arbitrary point and fills the interior of the triangle ΔBGH in the same manner as described above, the processor 1 selects the coordinate value XI of the second point G stored in the RAM 3.
Y? A deletion mark is added to the point G, and from now on, point G is treated as not existing.

Next, the processor 1 selects, for example, point B as an arbitrary point and fills the inside of the triangle ΔBHA in the same manner as described above, and then the coordinate value of the second point H stored in the RAM 3
□Add a deletion mark to Y8 and treat point H as not existing from now on.

When the processor 1 has two coordinate values to which no deletion mark has been added among the coordinate values stored in the RAM 3,
It is determined that the filling process is completed. This is because there are no triangles to fill.

FIG. 4 is a flowchart explaining the operation of FIG. 2.

The processor 1 selects a point at the end of a step from the coordinate values of points successively connected in the right direction in the RAM 3, for example, and reads out this coordinate value. Then, in step (2), it is checked whether there is a deletion mark in the coordinate values of point A, and if a deletion mark is attached, the process returns to step (2) and a new point A is selected.

If no deletion mark is given in step (2), then in step (2) eight points are selected and their coordinate values are read. Then, in step (2), it is checked whether there is a deletion mark at the coordinate values of the eight points, and if a deletion mark is given, the process returns to step (2) and a new point is selected.

If no deletion mark is given in step (2), vector AB is determined in step (2). Then, in step (2), the 0 point is selected and its coordinate values are read out.

Then, in step (2), it is checked whether there is a deletion mark, and if a deletion mark is given, the process returns to step (2) and a new 0 point is selected.

If a deletion mark is not given in step (2), the cross product of vectors AB and ACO is calculated in step (2). and,
In step ■, check whether the 0 point is on the right side of the vector AB. If it is not on the right side, return to the process of step ■. If it is on the right side, check whether there are other points inside the triangle ΔABC in step [phase]. investigate.

If another point exists within the triangle ΔABC in step [phase], the process returns to step (2), and if no other point exists within the triangle ΔABC, the interior of the triangle ΔABC is filled in in step (2).

Then, in step @, a deletion mark is added to the coordinate value of RAM 3 indicating 8 points, and in step @, it is checked whether the number of points to which no deletion mark is added is 2, and if it is greater than 2, the process returns to step ■. When it reaches 2, the operation ends.

Note that the calculation for calculating the outer product of vectors AB and AC requires only a product-sum calculation, so it is easy to implement in hardware and the calculation time is short. In addition, the time it takes to check whether there are other points within the triangle ΔABC is that there are many points at first, but as deletion marks are added sequentially, the number of points to be matched decreases, so it takes less time on average. time is not required.

〔Effect of the invention〕

As explained above, since the present invention determines the triangle to be filled with reference to the coordinate values, there is no need to search for the character outline developed in the image memory, and the present invention eliminates the need to search for the character outline developed in the image memory, and allows the user to draw characters using vector fonts with good character quality. Because it speeds up filling, it is possible to draw high-quality characters at high speed.

[Brief explanation of the drawing]

FIG. 1 is a process flowchart showing the configuration of the present invention, FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention, FIG. 3 is a diagram explaining the operation of FIG. 2, and FIG. 2 is a flowchart illustrating the operation of FIG. 2. FIG. In the figure, ■ is a processor, and 2 is a ROM. 3 is a RAM, 4 is an image memory, and 5 to 9 are processing steps. Qjl Yozuki f) 414AAti7su5kuri,'>L
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Claims (1)

[Scope of Claims] Coordinate values indicating the positions of reference points of vectors for drawing outlines of characters are successively stored in the order in which the outlines are drawn,
In the process of a character information output device that creates a character by filling in the inside of a character outline drawn as a vector based on the stored coordinate values, a coordinate value corresponding to an arbitrary reference point A among the stored coordinate values is determined. Based on the coordinate values of the reference point B adjacent to the reference point A and the coordinate values of the reference point C adjacent to the reference point B, the cross product of the vector AB and the vector AC is calculated (5), and the reference point C is determined. Check whether the reference point C is inside the character outline for the vector AB (6), and if the reference point C is inside the character outline, check whether there is another reference point inside the triangle ΔABC. Inspection (7): If there is no other reference point inside the triangle ΔABC, fill out the interior of the triangle ΔABC, add a deletion mark to the coordinates of the reference point B, and remove it from subsequent processing. (8), and if the reference point C is not inside the character contour, the triangle Δ
If there are other reference points inside ABC and if the interior of the triangle ΔABC has been filled, by setting a new arbitrary reference point A and repeating the above operation,
A vector font drawing method characterized in that the filling operation is ended when the number of reference points of the vector to which the deletion mark is not added reaches 2 (9).